Telephone ringing control circuits

Details Telephone ringing control circuits Telephone ringing control circuits

1975-12-05

1977-05-24

Cooper, William C.

Electrical transmission or interconnection systems

Nonlinear reactor systems

Parametrons

179 25R, 307253, H04M 126

Patent

active

040257290

ABSTRACT:
A single channel carrier system is disclosed including a remote terminal having a battery charger for charging a battery during idle periods to power the remote carrier electronics. The remote electronics include a ringing generator and a supervisory circuit to implement normal telephone supervision over the carrier channel.
The ringing generator is a dc-to-dc converter for stepping the battery voltage up to the ringing voltage level. In order to interrupt this unipolar ringing voltage and thereby to energize the telephone ringer, a switching circuit is provided including a transistor in shunt with the ringing voltage supply to provide a return path for alternate half cycles of ringing current. A constant current source from a low voltage supply connected to the base of the transistor provides bias current to saturate the transistor yet minimizes the amount of dissipated power.

REFERENCES:
patent: 3471650 (1969-10-01), Birck
patent: 3475561 (1969-10-01), Krasin
patent: 3536852 (1970-10-01), Dolarmore
patent: 3601538 (1971-08-01), May
patent: 3628066 (1971-12-01), Surprenant
patent: 3681621 (1972-08-01), Downs
patent: 3714469 (1973-01-01), Uchida
patent: 3904833 (1975-09-01), Beene

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